I am using an iCarsoft scan tool specifically for MB. I believe this one should have no problem erasing codes and pulling the car out of limp mode.

I can't seem to communicate with the TCM at all, even though all wiring now appears to be sound and the TCM itself looks perfectly fine, as does all of it's wiring. No fluid ingress, nothing at all.

What could be causing this? Is there something here I am overlooking? I would think that as long as the wiring to the transmission and the TCM are sound, then it should be able to communicate, correct? Other reason would be a totally dead TCM, but how often does that happen? Also, why would my shift indicator work with TCM plugged, and not without it? Surely that has to be a sign that it is at least powering on?

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Current cars:
2000 ML55 AMG, 174k miles
2003 C240 T-Modell, 202k miles
1995 S320, 207k Miles